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| Author | de Vries, H.; Stevens, J.M.G.; Vervaecke, H. | ||||
| Title | Measuring and testing the steepness of dominance hierarchies | Type | Journal Article | ||
| Year | 2006 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 71 | Issue | 3 | Pages | 585-592 |
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| Abstract | In the analysis of social dominance in groups of animals, linearity has been used by many researchers as the main structural characteristic of a dominance hierarchy. In this paper we propose, alongside linearity, a quantitative measure for another property of a dominance hierarchy, namely its steepness. Steepness of a hierarchy is defined here as the absolute slope of the straight line fitted to the normalized David's scores (calculated on the basis of a dyadic dominance index corrected for chance) plotted against the subjects' ranks. This correction for chance is an improvement of an earlier proposal by de Vries (appendix 2 in de Vries, Animal Behaviour, 1998, 55, 827-843). In addition, we present a randomization procedure for determining the statistical significance of a hierarchy's steepness, which can be used to test the observed steepness against the steepness expected under the null hypothesis of random win chances for all pairs of individuals. Whereas linearity depends on the number of established binary dominance relationships and the degree of transitivity in these relationships, steepness measures the degree to which individuals differ from each other in winning dominance encounters. Linearity and steepness are complementary measures to characterize a dominance hierarchy. | ||||
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| Call Number | refbase @ user @ | Serial | 454 | ||
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| Author | Poisbleau, M.; Fritz, H.; Valeix, M.; Perroi, P.-Y.; Dalloyau, S.; Lambrechts, M.M. | ||||
| Title | Social dominance correlates and family status in wintering dark-bellied brent geese, Branta bernicla bernicla | Type | Journal Article | ||
| Year | 2006 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 71 | Issue | 6 | Pages | 1351-1358 |
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| Abstract | In many gregarious species, including ducks and geese, being dominant provides more benefits than costs, because dominants have better access to resources essential for survival or reproduction. In geese, being in better body condition during migration towards the breeding grounds positively influences reproductive success. However, underlying proximate mechanisms linking prebreeding body condition on the wintering grounds to breeding success remain poorly understood. We investigated social dominance correlates and family status, in three consecutive winters, in a free-ranging, migrating, dark-bellied brent goose population. Families with juveniles dominated pairs, and pairs dominated singletons. Dominance rank did not increase with the number of juveniles per family. Males were dominant over females. Social dominance and reproductive status for a given winter were significantly correlated with body mass, body size and body condition during the previous winter, suggesting that body condition in winter also affects subsequent breeding success and hence also dominance. Levels of testosterone and triiodothyronine were not correlated with immediate or later dominance or reproductive status. We discuss the role of family status as a signal of social status in determining reproductive strategies. | ||||
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| ISSN | 0003-3472 | ISBN | Medium | ||
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Approved | no | |||
| Call Number | Equine Behaviour @ team @ | Serial | 4690 | ||
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| Author | Poisbleau, M.; Jenouvrier, S.; Fritz, H. | ||||
| Title | Assessing the reliability of dominance scores for assigning individual ranks in a hierarchy | Type | Journal Article | ||
| Year | 2006 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 72 | Issue | 4 | Pages | 835-842 |
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| Abstract | The dominance score (number of wins divided by the total number of interactions) is the most widely used procedure in field studies to rank individuals. Its reliability depends on the number of interactions on which it is calculated. However, most authors use it without any estimate of the associated error. We describe the precision associated with a dominance score estimate as a function of the number of interactions on which it is based, and hence provide a tool to plan field protocols and effort. The precision error decreases according to a power function with increasing number of interactions, but with more precision for extreme scores for any given number of interactions. We discuss the fact that the minimum number of interactions should be based on the precision associated with the 50% score, the least precise of all scores. We also emphasize the trade-off between recording effort and precision of the estimator, and give an example of our choice of 26 interactions for fieldwork on ducks and geese. When comparing individual ranks based on dominance scores with ranks given by the dominance matrix, we found a good correlation, with more mismatches around the middle of the hierarchy. This was consistent with the precision calculated with our model. We conclude that dominance score is a reliable tool, but conclusions must take into account the number of interactions on which the calculations are done. We also discuss the importance of initial assumptions and sources of bias in field studies. | ||||
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Approved | no | |||
| Call Number | refbase @ user @ | Serial | 456 | ||
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| Author | de VRIES, H.A.N. | ||||
| Title | Finding a dominance order most consistent with a linear hierarchy: a new procedure and review | Type | Journal Article | ||
| Year | 1998 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 55 | Issue | 4 | Pages | 827-843 |
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| Abstract | A procedure for ordering a set of individuals into a linear or near-linear dominance hierarchy is presented. Two criteria are used in a prioritized way in reorganizing the dominance matrix to find an order that is most consistent with a linear hierarchy: first, minimization of the numbers of inconsistencies and, second, minimization of the total strength of the inconsistencies. The linear ordering procedure, which involves an iterative algorithm based on a generalized swapping rule, is feasible for matrices of up to 80 individuals. The procedure can be applied to any dominance matrix, since it does not make any assumptions about the form of the probabilities of winning and losing. The only assumption is the existence of a linear or near-linear hierarchy which can be verified by means of a linearity test. A review of existing ranking methods is presented and these are compared with the proposed method. | ||||
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Approved | no | |||
| Call Number | refbase @ user @ | Serial | 457 | ||
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| Author | Cameron, E. Z.,; Linklater, W. L.,; Stafford, K.J.,; Minot, E. O., | ||||
| Title | Social grouping and maternal behaviour in feral horses (Equus caballus): the influence of males on maternal protectiveness | Type | Journal Article | ||
| Year | 2003 | Publication | Behavioral Ecology and Sociobiology | Abbreviated Journal | Behav. Ecol. Sociobiol. |
| Volume | 53 | Issue | 2 | Pages | 92-101 |
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| Abstract | The risk of infant injury or mortality influences maternal behaviour, particularly protectiveness. Mares are found in bands with a single stallion or bands with more than one stallion in which paternity is less certain. We investigated maternal behaviour in relation to band type. Mares in bands with more than one stallion were more protective of their foals, particularly when stallions and foals approached one another. The rate of aggression between the stallion and foal was a significant predictor of maternal protectiveness, and mare protectiveness was significantly correlated with reduced reproductive success in the subsequent year. Mares that changed band types with a foal at foot, or had their band type experimentally altered, were more protective of their foal in multi-stallion bands than they were in single-stallion bands. Equids are unusual amongst ungulates in that infanticide and feticide have been reported. Both occur where paternity has been uncertain, and equid social structure is similar to other species in which infanticide has been reported. Stallions benefit from infanticide as the mare has greater reproductive success in the subsequent year. Stallion aggression is a significant modifier of mare behaviour and maternal effort, probably due to the risk of infanticide. | ||||
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Approved | no | |||
| Call Number | refbase @ user @ | Serial | 458 | ||
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| Author | RHO, J.R.; SRYGLEY, R.B.; CHOE, J.C. | ||||
| Title | Behavioral ecology of the Jeju pony (Equus caballus): Effects of maternal age, maternal dominance hierarchy and foal age on mare aggression | Type | Journal Article | ||
| Year | 2004 | Publication | Ecological Research | Abbreviated Journal | Ecol. Res. |
| Volume | 19 | Issue | 1 | Pages | 55-63 |
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| Abstract | On Jeju Island, Korea, dominance hierarchy and maternal care according to maternal age were studied in a herd of Jeju ponies (Equus caballus), consisting of 73 mares, their foals and one stallion. Dominance ranks were nearly linear and increased significantly with the age of mares. Most aggressive encounters involved mares under 5 years old. Mares under the age of 5 years have apparently not established their rank. The mean frequency of aggressive actions of mares per hour increased significantly as the day of parturition approached. Aggressive actions of mares with foals decreased significantly as their foals aged. The overall frequency of aggression of mares with foals also decreased significantly with the age of the mares. Our results suggest that the cost of maternal care is lower for older, more dominant mares than for subordinate ones. | ||||
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Approved | no | |||
| Call Number | refbase @ user @ | Serial | 459 | ||
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| Author | Seyfarth, R.M.; Cheney, D.L. | ||||
| Title | The Structure of Social Knowledge in Monkeys | Type | Book Chapter | ||
| Year | 2003 | Publication | Animal Social Complexity: Intelligence, Culture, and Individualized Societies | Abbreviated Journal | |
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| Publisher | Harvard University Press | Place of Publication | Cambridge, Massachusetts | Editor | F. B. M. de Waal; P. L. Tyack |
| Language | English | Summary Language | Original Title | Animal Social Complexity: Intelligence, Culture, and Individualized Societies | |
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| ISSN | ISBN | 978-0674009295 | Medium | ||
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Approved | no | |||
| Call Number | refbase @ user @ | Serial | 464 | ||
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| Author | Hanggi, E.B. | ||||
| Title | The Thinking Horse: Cognition and Perception | Type | Conference Article | ||
| Year | 2005 | Publication | International Veterinary Information Service | Abbreviated Journal | AAEP |
| Volume | 51 | Issue | Pages | ||
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| Abstract | Cognition and perception in horses has often been misunderstood. Not only in the past but even today, people proclaim that horses react only by instinct, that they are just conditioned-response animals, that they lack advanced cognitive ability, and that they have poor visual capabilities (e.g., acuity, color vision, depth perception). Until relatively recently, there was little scientific evidence to address such beliefs. Change, however, is underway as scientific and public interest in all aspects of equine learning and perception intensifies. A review of the scientific literature, as well as practical experience, shows that horses excel at simpler forms of learning such as classical and operant conditioning, which is not surprising considering their trainability when these principles and practices are applied. Furthermore, horses have shown ease in stimulus generalization and discrimination learning. Most recently and unexpected by many, horses have solved advanced cognitive challenges involving categorization learning and some degree of concept formation. A comprehensive understanding of the cognitive and perceptual abilities of horses is necessary to ensure that this species receives proper training, handling, management, and care. | ||||
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| Language | English | Summary Language | Original Title | ||
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Approved | no | |||
| Call Number | refbase @ user @ | Serial | 465 | ||
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| Author | Feh, C. | ||||
| Title | Alliances and reproductive success in Camargue stallions | Type | Journal Article | ||
| Year | 1999 | Publication | Animal Behaviour. | Abbreviated Journal | Anim. Behav. |
| Volume | 57 | Issue | 3 | Pages | 705-713 |
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| Abstract | A study of a herd of Camargue horsesEquus caballus, showed that while the majority of high-ranking stallions held single-male harems, some sons of low-ranking mares, being low ranking themselves, formed alliances that could last a lifetime. The two stallions were each other's closest associate and preferential grooming partner. Alliances were based on coalitions in which either both partners confronted an intruder synchronously or the dominant of the pair tended the female(s) while the subordinate simultaneously displayed towards the rival. Alliance partners were of similar age but were not more closely related to each other than to other stallions in the herd. Long-term paternity data revealed that subordinates sired close to a quarter of the foals born into the alliance group, and significantly more foals than low-ranking stallions in the herd adopting a `sneak'-mating strategy. The dominant appeared to benefit from the presence of his subordinate partner. Fights occurred all year round, and the subordinate stallion of each alliance pair fought outside competitors more than twice as often as the dominant. Forming short-term alliances before defending mares on their own may enhance long-term reproductive success for both partners. Other benefits to both partners include higher survivorship of their foals and increased access to proven reproductive mares. These results suggest that the relationship between alliance partners is based on mutualism, but several conditions for reciprocity seem to be fulfilled: the benefit to the dominant (assistance in fights), and the benefit to the subordinate (access to reproduction), are both costly to the other partner and delayed in time. | ||||
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| Call Number | refbase @ user @ | Serial | 469 | ||
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| Author | Moons, C.; Heleski, C.R.; Leece, C.M.; Zanella, A.J. | ||||
| Title | Conflicting Results in the Association Between Plasma and Salivary Cortisol Levels in Foals | Type | Manuscript | ||
| Year | 2002 | Publication | Havemeier Workshop | Abbreviated Journal | |
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| Abstract | Introduction Glucocorticoids are present in many biological fluids as a free fraction or bound to Corticoid Binding Globulins (CBG) (Matteri et al, 2000). There are conflicting claims regarding the validity of saliva as a biological fluid to measure cortisol in horses (Lebelt et al, 1996; McGreevy and Pell, 1998; van der Kolk et al, 2001). Measuring changes in salivary cortisol levels in normal horses and horses with Cushing`s disease van der Kolk and collaborators (2001) demonstrated the validity of saliva to assess adrenal function. Puzzling results were reported by McGreevy and Pell (1998) who suggested that plasma and salivary cortisol concentrations in horses showing oral stereotypies were correlated but this association was non-existent in control animals. Investigating the responses of foals to branding and foot-trimming Zanella et al (unpublished results) were unable to identify a relationship between plasma and salivary cortisol levels in foals. In several species, levels of cortisol in plasma and saliva are tightly correlated (Fenske, 1996). Cortisol found in blood consists of a fraction bound to corticoid binding globulin (CBG) and a free, unbound fraction. Free cortisol represents the biologically active fraction of this steroid hormone. Salivary cortisol reflects the unbound fraction found in plasma or serum and it passes readily through the parotid membrane (Riad-Fahmy, 1983; Horning Walker et al,1977). Unbound steroids transfer rapidly between plasma and saliva (Walker,1989; Scott et al 1990). Saliva flow-rate does not appear to influence saliva cortisol levels in different species (Hubert and de Jong-Meyer, 1989; Walker 1989, Scott et a, 1990). In horses, Lebelt et al (1996) reported that salivary and plasma total cortisol in stallions were correlated. We hypothesized that changes in salivary cortisol in foals would show a pattern that is correlated to that of plasma free and plasma total cortisol concentrations in foals. In addition, we anticipated that the lack of good sampling techniques provides an explanation for the failure in determining the association between salivary and plasma cortisol in foals. |
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| Call Number | refbase @ user @ | Serial | 470 | ||
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